As so many other people have indicated, the remote control doesn't appear on the screen, and I can't seem to find any of the buttons that might make it appear.
Just tapping anywhere on the screen brings it up for me.
Also, there are buttons labeled as "custom" but I don't see any documentation on how to define what these buttons do.
Err.. How do you know that if you can't see the remote ? I'm confused.
Those buttons are defined when the remote is loaded onto your Slingbox during the setup process when you told the system what device you wished to control If you are using a built-in remote then the function mapped to each of the 15 possible Custom buttons are decided by Sling and you will just have to use trial and error. If you want to define each one yourself you will have to use a Custom Remote such as the ones I build for people.